1. Field of the Invention
The present invention relates to a method of and an apparatus for conveying an object by utilizing vibration which is obtained when an A.C. voltage is applied to, for example, a piezoelectric device or an electrostrictive device.
2. Description of the Related Art
A known type of apparatus for driving a driven member by utilizing a piezoelectric device is disclosed in, for example, U.S. Pat. No. 4,613,782. This known type of apparatus is capable of generating a large driving force, and is therefore suitable for use in conveying a heavy object. However, the apparatus has the disadvantage that it is not suitable for use in conveying an object of relatively low rigidity such as a lightweight object or a sheet material. In particular, it has been difficult to stably convey paper, a rubber sheet, a plastic sheet or the like by means of such a conventional apparatus.
An apparatus of the type disclosed in Japanese Patent Unexamined Publication No. 61-51435 is known as an apparatus for conveying a sheet material. This apparatus has an A.C. power source, an electrostrictive device, and a vibrator serving as a means for transmitting to a sheet material the vibration generated by driving the electrostrictive device. The vibrator has an end which is cut so as to form an acute angle, and the vibrator kicks a surface of the sheet material by means of its end to convey the sheet material. However, such a sheet-material conveying apparatus has the problem that since the sheet material is kicked out by the acute end of the vibrator when in contact with the sheet material, the surface of the sheet material is scratched. In addition, the end of the vibrator easily wears and its conveying capability deteriorates due to the wear. Accordingly, it is difficult to keep the conveying capability stable over a long period.